Deck 5: Development and Plasticity of the Brain

Question 1

The number of neurons in the brain is continually increasing throughout life.

Answer 1

False

Question 2

Proliferation is the production of new cells.

Answer 2

True

Question 3

The human central nervous system begins to form when the embryo is about 10 weeks old.

Answer 3

False

Question 4

The fluid-filled cavity within the neural tube becomes the central canal of the spinal cord and the four ventricles of the brain.

Question 5

Exercise may account for some of the neural benefits that come from rearing rats in an enriched environment.

Question 6

The developing infant brain is highly resistant to damage.

Question 7

The brain requires millions of chemicals to correctly guide the growth of axons to their target locations.

Question 8

Myelination of the brain and spinal cord is complete by the time of birth.

Question 9

Apoptosis is distinct from necrosis, which is death caused by an injury or a toxic substance.

Question 10

Recent evidence suggests that adult vertebrate brains generate new neurons.

Question 11

Mammals and amphibians are similar in that they can both easily generate new axons.

Question 12

After cells have differentiated as neurons or glia, they migrate.

Question 13

A rat in a more stimulating environment develops a thicker cortex, more dendritic branching, and improved learning.

Question 14

Axons are usually formed before the dendrites.

Question 15

Synaptogenesis is a process that begins before birth and continues throughout life.

Question 16

Nerve growth factor is a chemical that promotes the survival and activity of neurons.

Question 17

An early and fast stage of neuronal development is myelination.

Question 18

Physical exercise is important for increased dendrite growth and branching.

Question 19

Some neurons provide the myelination for other neurons.

Question 20

Once the brain is fully developed, the anatomy of the brain is unchanging.

Question 21

One effective method to overcome diaschisis after brain damage is to administer stimulant drugs.

Question 22

Paralysis caused by spinal cord injury is usually only temporary in humans.

Question 23

When do the ventricles and the central canal of the spinal cord form?

A) shortly after birth in humans
B) just as the forebrain starts its rapid phase of growth
C) early in embryonic development
D) during the third trimester

Question 24

Recent evidence suggests that phantom limb pain is caused by sensations coming from the stump of the amputated limb.

Question 25

The ability of the brain to change its anatomy over time, within limits, is known as:

A) plasticity.
B) regression.
C) connectivity.
D) long term potentiation.

Question 26

Diaschisis refers to the decreased activity of surviving neurons after damage to other neurons.

Question 27

Proliferation is the:

A) production of new cells.
B) movement of primitive neurons and glia.
C) formation of dendrites and an axon.
D) insulation process that occurs on some axons.

Question 28

Proliferation occurs:

A) at the top of the spinal column.
B) around the vesicles.
C) around the ventricles.
D) at the expanding edge of the brain.

Question 29

An axon in the peripheral nervous system is more likely to recover after being cut than if it is crushed.

Question 30

The fluid-filled cavity of the developing neural tube becomes the:

A) forebrain.
B) midbrain.
C) spinal cord.
D) ventricular system.

Question 31

Stem cells are important for which of the following developmental processes?

A) migration
B) proliferation
C) myelination
D) synaptogenesis

Question 32

The most common cause of brain damage in children is closed head injury.

Question 33

In strokes caused by ischemia or hemorrhage, neurons die from overstimulation.

Question 34

Deafferentation of the left arm results in the inability to move it.

Question 35

The human central nervous system:

A) begins to form during the fetal stage.
B) is unlike all other vertebrate central nervous systems in its developmental process.
C) begins to form when the embryo is about two weeks old.
D) begins to form when the embryo is about two months old.

Question 36

What is the production of new neurons called?

A) differentiation
B) migration
C) myelination
D) proliferation

Question 37

The damaging effects of a stroke can be limited if treated within a short period of time.

Question 38

As the neural tube sinks under the surface of the skin, the forward end enlarges and differentiates into the:

A) spine, midbrain, and forebrain.
B) hindbrain, midbrain, and forebrain.
C) hindbrain, midbrain.
D) midbrain, forebrain.

Question 39

Early in development, the nervous system begins as a:

A) tube surrounding a fluid-filled cavity.
B) spherical structure in the center of the embryo.
C) diffuse system of cells scattered throughout the body.
D) single layer of cells covering the heart and other internal organs.

Question 40

Denervation supersensitivity results from the disuse of incoming axons.

Question 41

For some axons, glial cells produce an insulating sheath that makes rapid transmission possible. What is this process called?

A) Differentiation
B) Migration
C) Myelination
D) Proliferation

Question 42

What is the process called when a primitive neuron begins to develop dendrites and an axon?

A) Differentiation
B) Migration
C) Myelination
D) Proliferation

Question 43

The final stage of neurodevelopment is called:

A) synaptogenesis.
B) differentiation.
C) migration.
D) fusion.

Question 44

The stages of neurogenesis that occur for the longest duration are:

A) myelination and synaptogenesis.
B) proliferation and myelination.
C) migration and proliferation.
D) differentiation and migration.

Question 45

After cells have differentiated as neurons or glia, they:

A) differentiate.
B) proliferate.
C) myelinate.
D) migrate.

Question 46

Migration requires:

A) a precise chemical environment.
B) cells which are myelinated.
C) mature neurons.
D) neurons with fully developed dendrites.

Question 47

The formation of new synapses is called:

A) synaptogenesis.
B) differentiation.
C) migration.
D) fusion.

Question 48

What term describes the movement of primitive neurons and glia within the developing nervous system?

A) Differentiation
B) Migration
C) Myelination
D) Proliferation

Question 49

Immunoglobulins and chemokines play an important role in neural:

A) migration.
B) proliferation.
C) synaptogenesis.
D) apoptosis.

Question 50

Which of the following best characterizes how axons arrive at the correct target cells?

A) They follow electrical gradients.
B) They follow chemical gradients from the target cell.
C) Axons send out chemicals to the target cells.
D) Target cells send out branches for the axons to follow.

Question 51

Which of the following would most likely interfere with migration of neurons during development?

A) altering the chemical paths
B) damaging dendrites
C) loss of myelin
D) increased differentiation

Question 52

In humans, myelination first occurs in the:

A) spinal cord.
B) hindbrain.
C) midbrain.
D) forebrain.

Question 53

Myelination is a process common to:

A) all vertebrate axons.
B) all vertebrate dendrites.
C) some vertebrate axons.
D) some invertebrate axons.

Question 54

The formation of a neuron's distinctive shape occurs during the ____ stage of neurogenesis.

A) proliferation
B) migration
C) differentiation
D) myelination

Question 55

Whether or not a transplanted immature neuron adopts the properties of neurons in the new location or retains at least some properties of neurons from where it was taken from depends largely on how much the transplanted neuron has:

A) myelinated.
B) proliferated.
C) migrated.
D) differentiated.

Question 56

Chemicals known as ____ and ____ guide neuron migration.

A) immunoglobulins; sodium
B) glia; neurothrophins
C) immunoglobulins; chemokines
D) chemokines; neurothrophins

Question 57

Migration is the:

A) production of new cells.
B) movement of primitive neurons and glia.
C) gradual formation of dendrites and an axon.
D) insulation process that occurs on some axons.

Question 58

After the migrating neuron reaches its destination, ____ begin to form.

A) dendrites
B) axons
C) nuclei
D) ganglions

Question 59

Differentiation is the:

A) production of new cells.
B) movement of primitive neurons and glia.
C) formation of dendrites and an axon.
D) insulation process that occurs on some axons.

Question 60

Myelination in the human brain:

A) is complete upon birth.
B) is complete around the second birthday.
C) is complete sometime shortly after adolescence.
D) continues well into the adult years.

Question 61

The concept that neurons refine their many connections based on which ones are most successful is known as:

A) natural selection.
B) evolution.
C) survival of the fittest.
D) neural Darwinism.

Question 62

Why is it that all neurons in a healthy adult brain have made appropriate connections?

A) Chemical messages from our muscles tell our brain how many neurons to form and that number perfectly matches the connections required.
B) If an axon does not make the appropriate connections by a certain age, it dies.
C) We are born with all connections formed.
D) Connections form rapidly, but we learn to use whatever connections have formed.

Question 63

What process occurs when axons attempt to form connections to a grafted limb in a salamander?

A) Axons connect randomly, but only muscles "tuned" to the right message respond.
B) Axons connect randomly and muscles learn to coordinate through experience.
C) Axons find their way to corresponding muscles in the new leg.
D) A lack of nerve growth fiber leads to the degeneration of the new leg.

Question 64

Which of the following are selective as axons form synapses with target cells?

A) axons, but not target cells
B) target cells, but not axons
C) both axons and target cells
D) neither axons nor target cells

Question 65

Why is it that every axon in an adult mammal has a target cell (muscle cell or other neuron) with which it makes synaptic contact?

A) Each target cell causes the growth of a neuron and its axon.
B) After formation, axons release a chemical that causes a target cell to form.
C) Axons that fail to find a target cell die.
D) An axon will make contact with any kind of cell and adjust its function as necessary.

Question 66

Competition of neurons for postsynaptic sites results in survival of only the most successful axons. This general principle is called:

A) natural selection.
B) evolution.
C) apoptosis.
D) neural Darwinism.

Question 67

Axons sort themselves over the surface of the target area:

A) by following a gradient of chemicals.
B) through apoptosis.
C) through necrosis.
D) based on their size.

Question 68

What visual capabilities did Sperry's newt have after Sperry cut the optic nerve and rotated the eye?

A) It regained normal vision.
B) It saw the world upside down and backwards.
C) It required experience to relearn how to see.
D) It remained blind.

Question 69

What is signaled by nerve growth factor (NGF)?

A) That a target cell has "accepted" an axon
B) Which target cell a growing axon should connect with
C) That axons should elongate as the body grows bigger
D) The need for new neurons to form in brain areas that are lacking in neurons

Question 70

New neurons are known to develop in all of the following cases EXCEPT:

A) olfactory receptors.
B) the human corpus callosum.
C) the brain area responsible for birdsong.
D) hippocampus of mammals.

Question 71

If you cut the optic nerve of a newt, what happens?

A) The fibers grow back and attach to random targets, so they see a scrambled picture.
B) The fibers grow back and attach to their original targets, resulting in normal vision.
C) The newt remains blind, since neurons do not regenerate.
D) The fibers attach to multiple targets, resulting in blurry vision.

Question 72

When Sperry cut a newt's optic nerve and rotated the eye by 180 degrees, each axon:

A) degenerated.
B) regenerated to a random location.
C) regenerated to the area where it had originally been.
D) regenerated, but to the area appropriate to its new location.

Question 73

Brain cells that are neither neurons nor glia, but which are capable of dividing and then differentiating into neurons or glia, are called:

A) parallel fibers.
B) intrinsic cells.
C) stem cells.
D) glomeruli.

Question 74

Roger Sperry cut a newt's optic nerve and rotated the eye. Axons from what used to be the dorsal part of the retina (now located on the ventral side) grew back to the target areas:

A) that ordinarily get input from the dorsal retina.
B) that ordinarily get input from the ventral retina.
C) that ordinarily get input from the center of the retina.
D) equally and diffusely.

Question 75

What happened when Weiss grafted an extra leg onto a salamander adjacent to one of the hindlegs?

A) The new leg gradually took over for the old.
B) The new leg withered and died.
C) Nerves from the old leg attached to the new in a random fashion.
D) Branches of axons from the old leg attached to corresponding muscles in the new.

Question 76

Chemicals in the amphibian tectum guide the growth of axons from the retina to their correct location in the tectum by:

A) having dozens of different growth factors.
B) using an electrical gradient.
C) using a chemical gradient.
D) glial cell transportation.

Question 77

What is meant by neural Darwinism?

A) The brains of higher primates are the ones that are most similar to those of humans.
B) Most individual differences in the brain are due to genetic mutations.
C) Successful neurons develop while less successful neurons weaken or die.
D) Successful neurons reproduce while less successful neurons do not.

Question 78

As a rule, all vertebrate neurons develop during an embryological stage. Among the few types of neurons that can develop in adulthood are:

A) ganglion cells in the retina.
B) olfactory receptors.
C) motor nerves in the spinal cord.
D) long-axoned neurons of the primary motor cortex.

Question 79

____ steer new axonal branches and synapses in the right direction.

A) Chemokines
B) Immunoglobulin
C) Glia
D) Neurotrophins

Question 80

Which of the following best describes the process by which developing axons find their general target areas?

A) completely random growth
B) shape attraction
C) electrical attraction
D) chemical attraction